(I put the tofu in parentheses, below, because I didn't have it, and didn't need it, ending up with plenty of "stuffing" without it. The half zucchini I used was still pretty huge.)
Preheat oven to 425° F (220° C, Gas Mark 7)
8-12 open-cap mushrooms for stuffing - about 8 oz. mushrooms
1 small leek or onion, chopped
1 celery stalk, chopped
1 carrot, chopped
1 small zucchini (courgette) chopped
(3 1/2 oz. firm tofu, diced)
1 cup (whole wheat) breadcrumbs
2 Tbs chopped fresh basil, or 1 Tbs dried basil
1 Tbs tomato paste or cocktail sauce
2 Tbs pine nuts
1 Tbs olive oil for saute
2/3 cup vegetable stock
3/4 cup grated hard cheese (or just a light sprinkling)
Salt (about 1/2 tsp) and (freshly ground) pepper- in salting take into account the saltiness of the cheese and the stock.
Remove stems and "flash" from caps, arrange caps in small oven dish, about 8" square.
Chop stems and loose pieces of mushrooms; saute along with leek/onion, carrot, and zucchini in olive oil on medium heat, about 4 minutes.
Add breadcrumbs, basil, tomato paste and pine nuts to veggie mix. Season with salt and pepper to taste. Mix well. Stuff as much as you can into the mushroom caps, then spread the rest over them.
Pour vegetable stock around mushrooms, cover with grated cheese, and bake in preheated oven (see above) for about 20 minutes. Mushooms will still be moist from stock. If you have oversalted, or want to take up some liquid, this goes great over rice.